Plaster or cement composition and method of making the same.



lUfi. UUMPUSI l IUNS,

COATING R PlAST'C UllUbb lilll'tlililllil:

nanny s. rnaronnn, or LOS AnoELEs, camronnm, ASSIGNOR TO cnnrrn rnonucrs comranx, or LOS ANGELES, CALIFORNIA, A conronarron or camronnra.

PLASTER OR CEMENT COMPOSITION AND METHOD OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

-Be itknown that I, HARRY S. Tnarcrma, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a s new and useful Plaster or Cement Compositic nature as to sprea [the ordinary plaster, and which will form vide a plaster when set, a smoother, finer grained surface than the ordinary plaster.

Another object of the invention is to prowhich is adapted to make walls or other building constructions of unusually high heat resisting quality, as well as high insulating quality for heat and sound.

My improved plaster or cement contains,

as essential constituents. calcined gypsum and a porous non-er stalline siliceous mate- .rial havingcolloida properties. The noncrystalline siliceous material I prefer to use .is ln'eselguhr or infusorial earth, but other non-cr stalline siliceous materials may be used, or example, tufa'or like materials.

;The kieselguhr used is preferably the airdried product and the gypsum is used in calcined or burnt condition (plaster of Paris). The kieselguhr and calcined gypsum are mixed in. such manner as to form an intimate mixture of finely divided g psum and finely divided porous non-crystalline silica.

For the purpose of makin the material as light as possible it is desira le to incorporate a' considerable percentage of kieselguhr with the plaster of Paris, or gypsum, but in mixing the gypsum with any large percentage of kieselguhr the productsis liable to be. weakened by the presence of loose kieselguhr, un-" cemented b This is particularly 'the case w on the kieselguhr and gypsum are mixedindry condition, so astov form a dry powdered product, suitable for saleas 'such, and ready for use by simply mixing with water. In order to PI'OVIdQ a dry Specification of Letters Patent.

Application filed June 17, 1916. Serial No. 104,166.

Patented Jan. 1, 1918.

plaster composition of uniform composition and adapted to form a firm, strong plaster when mixed with water and allowed to set, it is necessary to bring the kieselguhr intointimate contact and thorough mixture with the calcined gypsum and I accomplish this by intergrinding the kieselguhr and callllll cined gypsum in such a manner that a more intimate contact and a more thorough mixture of the said constituents is secured than is practicable by simply mixing them in the usual way.

Both the kieselguhr and the plaster of Paris may be ground to a moderate degree of fineness before the are interground, or

. they may bemixed 1n a coarsely crushed state and then' intergi'ound, the grmding being preferably such as to reduce the mixture to a. fineness of about 200 mesh or finer.

Any suitable proportions of kieselguhr and plaster of Paris may be used, for example, 20 to 30 per cent, by weight of kieselguhr and to 70 per cent. by weight of plaster of Paris or calcined gypsum.

By intergrinding the non-crystalline silica with the calcined gypsum I am enabled to use a largerproportion of such non-crystal.-

line silica than would be practicable by simply mixing these constituents, while retaining the full strength of the plaster or even increasing such strength. The product a is also of especial advantage in plasters in that the colloidal silica acts, as a retarder for the plaster,- dispensing with the use of organic retarders. The presence of the kieselguhr in the comparatively large proportion stated, amounting to say two parts of kieselguhr by volume to one part of plaster, greatly increases the plasticity and smoothness of working of the plaster. owing to the colloidal property of the kieselguhr and the tendency to absorb and retain water. .On account of the colloidalproperty of the kieselguhr and its intimate mixture with the calcined gypsum, a firmer bond is secured between these constituents and a stronger and more durable plaster or cement is produced, when the plaster is mixed with water.

The comparatively large volume of kieselguhr" which it is possible to introduce into the plaster by intergrinding renders :the

product much lighter than ordinary plaster, and due to the fineness to which the kieselguhr. is ground it is possible to secure a much smoother finish than is possible with ordior barrels like ordinary plaster and sold in that condition for use together with water or with water and sand or other filler, in

making plaster for walls or for other purposes, or for use as a cement.

In some cases, lime, either in the form of quicklime or of calcium hydrate, may be added to the mixture to'reduce the acidity of the composition or for other purposes, and in such cases the lime is also. referably interground with the non-crystal ine silica and calcined gypsum.

What I claim is:

1. A laster'or cement composition com-' prising e1 divided porous non-crystalline silica and'ca cined psum, in a state of intimate contact and mlxture.

2. A plaster or cement composition comprisin porous non-crystalline silica having 'colloi al properties and calcined gypsum ground together toform an intimate mixture. "1 I 3. Thefprocess of making a plaster or cement c'om osition which consists in intergrinding cacined gypsum with porous noncrystallme silica.

4. A laster or cement composition comprising ieselguhr interground with calcined gypsum.

In testimony whereof I have hereunto set my hand, at Los Angeles, California, this 5t day of June, 1916.

'HARRY s. THATOHER. -Witnesses:

- W. Dm'mnnn,

G. F. Gnm'rrn. 

